# What is Soderberg line?

Q.  Line joining Syt (yield strength of the material) on mean stress axis and Se (endurance limit of the component) on stress amplitude axis is called as _____
- Published on 14 Sep 15

a. Goodman line
b. Soderberg line
c. Gerber line
d. None of the above

#### Discussion

• Ranadheer durgi   -Posted on 12 Sep 17
Good definitions
• Sravanthi   -Posted on 03 Nov 15
1) Soderberg line:

- Line joining Syt (yield strength of the material) on mean stress axis and Se (endurance limit of the component) on stress amplitude axis is called as Soderberg line. This line is used when yielding defines failure.

- (σm / Syt) + (σa / Se) = (1 / Nf) is the equation for Soderberg line.

2) Goodman line: Line joining Se on stress amplitude axis and Sut on mean stress axis is known as Goodman line. Triangular region below this line is considered safe.

- Equation for Goodman line is (x/a) + (y/b) =1

3) Gerber line: Se on stress amplitude axis and Sut on mean stress axis is joined by a parabolic curve.

- The equation for Gerber criteria is (Sm / Sut)2 + (Sa / Se)2 = 1

here, Sa = limiting safe stress amplitude, Se = endurance limit of component, Sm = limiting safe mean stress, Sut = ultimate tensile strength.

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